The present invention relates to flexible fire protective insulating barriers for inhibiting the spread of fire within buildings and other structures.
In many countries, building regulations require the installation of fire resistant barriers between floors and other cavities. Conventional cavity barrier systems are made of either glass fiber or mineral wool. These materials are typically woven into blankets or pressed into sheet or blocks, and their outer surfaces are often coated with an intumescent material for enhanced performance. Intumescent coatings react to heat in excess of 100.degree. C. to give a carbon char with high insulating properties. Cavity barriers of this type are heavy, must be assembled on site, and do not easily accommodate pipes, ducts, and other services which must pass through the barrier. Installation costs associated with these conventional cavity barriers are also high because of the labor required to cut and fit them into place across a given opening.
It has also been proposed in U.S. Pat. No. 4,292,358 to fire-proof ceilings, partitions, and the like with flexible barriers comprised of a single metal foil of aluminum sandwiched between a number of expanded metal sheets that have been coated on one or both sides with a heat actuated and resistive intumescent coating. The application of the intumescent coating is usually carried out by spraying under controlled factory conditions. Barriers constructed of this type are lightweight and are easier to cut and install than those of the fibrous type described above. However, the relatively low thermal conductivity and hot strength of the aluminum used in the construction of the foil and expanded sheets render such barriers unsatisfactory at very high temperatures. Also, when exposed to fire, the intumescent coatings generate large amounts of dense, acrid smoke.